Investing machine



g. 12 1952 E. L; H'ILDRETH I 2,606 347 INVESTING MACHINE Filed Nov. 25, 1949' i; QQ

I INVENTOR. EBA/57 L. 010257 2B 25 1 29 fl/V'OE/VEV Patented Aug. 12, 1952 UNITED STATES OFFICE mvnsrmo Ernest l l li ldretlnlosAnge les, Calif. Application November 25, l9 49, Serial tea-r13 The present invention relates to an investing machine :of, the type adapted for. investing 'wax patterns for dentaland small industrial castings;

An object ofthe invention is the-provision of an investing machine of simple construction, easy to operate, and capable of producing superior: re-

sults.

A smooth and accurate plaster'matrix of 'axwax patternisassured by the present invention.

"A further object is the provision of an investing machine adapted to 'centrifugeithe:investment material about'the pattern an'din such amanner that the investment material is :densely packed,

1 and substantially free from :gases. and excesszwater.

A further obj'ectis the provision ofan investing machine of attractive appearance;wherein certain of theoperationsto be performed by the machine may be observed, and which machine is generally superior to devices nowknown toithe inventor.

With the above-mentioned objects, including simplicity of structure and. inexpensiveness in ;cost of manufacture, the invention consists in the novel and useful provision, formatiomconstruction, association and relative arrangement: of parts, members and features, all 'a'sashowninicertain embodimentsain'theaccompanying drawing,

ydescribed generally, and more particularly pointed .outin the claims. r

1 In the drawing:

Figure 1, is atop. plan :viewof one form of the 1 invention; a

.larged scale on the line 6--6 of'Figure 4.

Referring now with particularity to'the drawing, the investing machinein'cludes a casing having an annular. side wall I, a base 2 ,and a rubber disc. 3- positioned between the wall I. and" base.

Within theconfines ofthe casing isanenlarged annular block'fl supported on the disc 3.1 Block 4 surrounds a motor. 5 secured to vertical posts 6;

the posts being mounted on the member 3. The block 4 is recessed at I and the base 2.is.formed withxa' bore permitting passage of an electrical cable 8 into the easing forconnection with the motorjas shown. The shaft of the motor stands a Qlaims. (oi. 312%6154.)

;-vertically and substantially in. the axis-oi the :casing; the:::said-;Shaft'supporting {or rotation a ;.'spider 9. The spider 9 in-the present instance is .secured to the motor shaft in anvapproved manner; such ass-by thenut 51-!) and said-spider is 'provided with four e'qui-distantly spaced-apart arcurate-:recesseswH, .452, i3 and 14; the construction .QIJIOVJ IGiHg four. spaced pairs of arms as -indicated 'at 1 5 andi-B fOIrGIIBypBfiT. :Rings ijzare meunted between 'each pairfcharms (see. Figure 5) .i'lhe rings"are' diametric'ally held-by screws "designated generally? "it which are 1 transversely :::passed through thearms for engagementiwith the ring,

- there being a sp'acer memberi's carried on each ring-in e'ach instance. 1

The form-of the 'invention shown in Figures 2 and 4 does not difier essentially from rthei form in 'Figu-re 1"and'i'3, -sav'e and except that two spaced pairs of arms are provided; as indicated a-t 2'0 "and" 2 l, and mquntedbetween said armsare rings 22. *The Z2 ai-elarger in iameter than the rings '1 l 'a ndfor reasons which screw and interposed betwe'en i the farmsrand'zthe will hereinafter appear;

In the practice" of th'atform of the invention shown in 'Figures 1-and"3,I utilize'iour cups or buckets 23 of the form shown' 'im i' igure' "5.

. Each bucket err-cup is provided with an 'outturned lip or iiangeitwhichiip is adapted to engage 'theuppersurfaceot the ring H for supporting the cup. The cup or bucket is ore/size which permits receptiontherein Of'a, sprueformer 25, an investmentring 26 carried "by, the/sprue 'forinenand "ahopp'er" 2'l ,"'supported on the .upper end or the investment r g. The spru'e' former {has the usual convex crucible forming portion 28, provided with anaxial'bor adapted "to receive sprue pin at. .T e spru'e rpm carries a pattern 3| (ifsomforml .l ,1 Thehopper' 2'! has a base 32, the outer surface of.whichisrecessedltoprovidean annularjiia'nge .33, which flange. surroundsthelupperfendoi.the

investmentr'ing. j' Ifl'iefside .wall of lthel h'opper is conicaL win iorin. and provided with an "enema annular bead 34, which. bead isladapted't'dfengage'the inner surface of the bucketor cup for stabilizing. the hopper] surface of the side wallis inclined or conical in for-r n for the purpose-of,- directingany material therjein toward I a central per-ioration' 5 in the-base. The, side wall andbaseis bOredvat-SB to provide a vent for'theinvestment ring. .Ihe hopper-adjacent its outermost: end is provided withaan annular 55.

shoulder -31-and-a .transparent' cap' 38 provided with a central perforation 39 is adapted to overlie the hopper and be positioned on said shoulder.

In the form of the invention shown in Figures 2, 4 and 6, the bucket or cup 40 has less depth and greater diameter than the bucket or cup 23. The investment ring 4| is internally shouldered at each end, as shown at 42 and 43, the lower shoulder engaging the shoulder 44 of a base member 45. A hopper 46 rests upon the shoulder 42. This hopper is provided with a central vent tube 41 which extends through the base 48 of the hopper. The base 48 is provided with a series of spaced radially arranged transverse perforations 49. This form of the invention is particularly adaptable for dentures.

The operation, uses and advantages of the invention just described is as follows:

Taking that form of the invention shown in Figures 1, 3, and 5, it is essential that the buckets, investment ring, sprue former, hopper and cap should all be of the same weight. In fact, the weight of investment material used in the respective hoppers should be the same. To this end,

' a scale is employed for weighing the said members. After the wax pattern 3| has been formed, and impaled on sprue pin 3|], the sprue pin is placed in the bore 29 of the sprue former and sprue former is placed in a bucket 23. The investment ring with its asbestos insert is then placed in position surrounding the pattern. Following this, the hopper is placed over the investment ring and the investment material in a weighed and measured quantity is poured into the hopper. The transparent cap is then positioned over the hopper, and the assembly has the appearance shown in Figure 5. As shown, four patterns and buckets may be utilized, or if only one pattern is used, then two assemblies are placed diametrically of the spider, with both assemblies holding a like weight of investment material.

A transparent cover 50 is provided for the casing, the cover being in gasket sealed relationship therewith, as shown at 5|. In the present instance, the base 2 is bored to accommodate a tube 52, which communicates with the bore of the annular block 4. This tube leads to a vacuum pump, not shown. The first procedure after investment material is placed in a hopper or two hoppers in diametric position, is to operate a valve leading to the vacuum pump, to the end that the entire casing is placed under vacuum. This condition may be determined by a gauge in the usual manner. While maintaining a vacuum within the casing, the motor 5 is energized which will cause the buckets to revolve on their pivots and assume an axially horizontal position. When this occurs, the investment material will be dimaintained, excess water and gas in the investment material,'with the result that the investment material is formed into a hard compact mold about the wax pattern.

Y After the investment material has been deposited from the hopper into the investment ring,

the material is allowed to set for a given period of time, as determined by the characteristics of the particular investment material selected.

Thereafter, the assembly may be removed from the buckets, the sprue pin removed, and the wax pattern burned from the matrix in the usual manner. It will be found that the use of centrifugal force and a maintained vacuum condition within the hopper and investment ring produces a very hard smooth matrix and one that gives perfect results so far as the resultant casting is concerned. It is obvious that the vent 36 allows gases to escape from the investment ring to the perforation 39 in the cap.

The entire assembly is held against movement within the bucket when the parts are in the position shown in Figure 5 with the annular bead 34 engaging the inner surface of the bucket. Vibration is no problem in the practice of the present invention, although it is a problem in the average centrifuge.

In the operation of that form of the invention shown in Figures 2, 4 and 6, the wax pattern 53 is shown in a support of investment material 54. This investment material has wire 55 embedded therein to give stability and aid in maintaining form. As before, the two assemblies, such as shown in Figure 6, are preferably weighed, so that there will not be vibration when the spider is rotated by the motor. The investment material is placed Within the hopper 46 and under centrifugal force, the investment material passes through the perforations 49 to surround the investment material 54 and to enclose the wax pattern 53. As before, gases, excess water and the like may pass through the vent tube 4! under vacuum conditions. Upon completion of the passage of the investment material from the hopper into the investment ring 41, the investment material is allowed to harden, whereupon the wax pattern may be melted therefrom, followed by the usual metal casting operation.

The present invention may be utilized for purposes other than the investing of wax patterns, as it may be used for making plaster casts or models which are centrifuged from the hoppers into the impressions.

I claim:

1. An investment machine, including: a casing, a motor and its shaft centrally positioned Within saidcasing; a spider carried by said shaft; said spider being provided with equi-distantly spacedapart arcuate recesses; a ring positioned within each recess; means for pivoting each ring to said spider; a bucket pendant from each ring; an investment ring and base member therefor within the bucket; a hopper supported on the investment ring; said hopper being formed with a side wall and a base, the base of which is provided with a perforation and a vent opening extending through the side wall from the base of the hopper to adjacent the top thereof, both the vent opening and said perforation communicating with the interior of the investment ring, and means for placing the interior of said casing under vacuum conditions.

2. An investment machine, including: a bucket, a sprue former carried by said bucket, an investment ring for said sprue former, a hopper carried by the investment ring, and a cap for the hopper, said hopper having a conical side wall, and a base, the said base being formed with an opening leading to the interior of the investment ring, said side wall of the hopper being provided with a bore extending from thetop of said wall through the base to provide a vent, the said vent communicating With the interior of the investment ring.

3. An investment machine, including: a casing, a motor and its shaft centrally positioned within said casing; a spider carried by said shaft; said spider being provided with equidistantly spacedapart arcuate recesses; a ring positioned within each recess; means for pivoting each ring to said spider; a bucket pendant from each ring; an investment ring and base member therefor within the bucket; a hopper supported on the investment ring; said hopper being formed with a side wall and a base; the base of which is provided with a perforation, said side wall of the hopper being provided with a bore extendin from the top of said wall through the base to provide a vent, both the vent and said perforation communicating with the interior of the investment ring.

ERNEST L. HILDRETH.

6 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,124,099 Adams Jan. 5, 1915 1,325,004 Davidson Dec. 16, 1916 2,009,489 Fritzsche July 30, 1935 2,037,618 Carpenter Apr. 14, 1936 2,147,103 McKee Feb. 14, 1939 2,359,524 Lane Oct. 3, 1944 2,385,631 Levinson Sept. 25, 1945 2,435,227 Lester Feb, 3, 1948 2,482,257 Frei Sept. 20, 1949 

